Archive for the ‘emulsion’

For me, winter is the best time of the year to make Lemon Curd. Why? you ask? Because winter is when I can find Meyer Lemons at the store. While I can certainly make lemon curd with regular lemons, I find Meyer Lemons have just the right mix of tart and sweet that take this lovely confectionary spread to the next level.

Meyer Lemons were grown in China for centuries and were introduced in the US in 1908 by F.N. Meyer. Botanists believe it is a cross between a lemon and an orange. It is generally larger, juicier, and less acidic than regular lemons. They are usually available from fall through early spring, with their peak season during the winter.

A Meyer Lemon (l) and a standard lemon (r).

Regular Lemon (l) and Meyer Lemon (r)

Now, wait, you may be saying. What is exactly Lemon Curd?

First, there are two types of curd:

1. Curd solids from milk. These solids are formed when rennet (or another acid) is used to separate the milk solids from the liquid (whey) during the cheese making process.

2. A sweet creamy spread that consists of (usually) citrus juice, egg yolks, sugar, and butter. It can be made with other fruit such as berries.

A curd is a type of sauce called an emulsion. The simplest explanation for this comes from The New Food Lover’s Companion: “A mixture of one liquid with another with which it cannot normally combine smoothly. Emulsifying is done by slowly adding one ingredient to another while at the same time mixing rapidly (usually whisking). This disperses and suspends tiny droplets of one liquid throughout the other. Emulsified mixtures are usually thick and satiny in texture.” Mayonnaise, vinaigrette, hollandaise, and bearnaise are all examples of emulsion sauces.

A few notes:

1. You can make this with regular lemons. Find lemons that feel heavy for their size. The final product will be more tart, but you can add some sugar to taste if you like after the curd is finished.

2. The best way to go about this is low and slow. If you show any impatience or lack of attention, you could easily over cook the curd and end up with sweet scrambled eggs.

3. Always have extra bowls on the side in case you need to move your curd to a cool, clean bowl.

4. Having an instant-read thermometer will come in handy. You want the curd to come to about 160F. It will be fully cooked at this point without scrambling the eggs (that is, if you are careful).

5. When using the double-boiler, the boiling water should never touch the bottom of the bowl. This will cause the eggs to cook too quickly.

6. You can make lemon curd into a preserve: Fill a half-pint jar with a 1/2″ head space and process the jars for 15 minutes. Take the canning pot off the heat and leave the jars in the hot water for a further 10 minutes, then take the jars out of the water, and place them on racks to cool and seal. Because of the nature of the curd, however, the texture will change during the processing, and it will only have a shelf life of 2 – 3 months because of the high dairy content.

The Ingredients

The lemon zest. I use a Microplane for mine. If you don’t have a Microplane, just very finely mince the zest.

3 egg yolks, room temperature

1 whole egg, room temperature

3/4 c. sugar

1/2 c. lemon juice (preferably Meyer Lemons)

Zest from juiced lemons

6 oz (10 tbsp.) butter, cut into 1/4″ cubes, softened

1. Combine the egg whites, whole egg, and sugar in a medium stainless steel bowl with either a whisk (if you have a lot of upper body strength) or a beater starting on medium-low speed and gradually increasing the speed and mix until the mixture becomes light, thick, and falls into a ribbon when the whisk or beaters are lifted from the bowl. (Doing this will help to begin the emulsion process, start dissolving the sugar, and begin to chemically cook the eggs.)

Early in the process. The mixture is still dripping unevenly. I kinda cheated here and used the electric beaters.

About 10 minutes later. The mixture is thickened and is falling much more smoothly from the beaters. If it doesn’t fall in a ribbon, you want the mixture to at least leave a “trail” in the bowl as it falls back in.

2. Carefully mix in the lemon juice and zest.

Adding the zest and juice.

3. Have a saucepan about 1/4 full of simmering water ready on the stove. Place the bowl with the lemon mixture on top. (You just want the bottom of the bowl to sit over the water.)

Setting up the double boiler: Fill the saucepan about 1/4 full of water. Make sure that the boiling water never touches the bottom of the bowl.

Have a second bowl on the side in case the mixture cooks too quickly and begins to curdle (that would be the eggs scrambling).

4. Stir the lemon mixture with the whisk constantly until the foam subsides and begins to thicken. Adjust the heat as needed (the easiest way to do this is to take the bowl from off the top of the saucepan, or, if the mixture is cooking too quickly, move the mixture to your second bowl; if you do move to a second bowl, very carefully scrape or do not scrape the original bowl – what’s left in the bowl is more than likely going to be scrambled).

Whisking the mixture. You want to do this fairly constantly until the foam subsides. Once this happens, the eggs will begin cooking much more rapidly. Again, remember – low & slow is the key

The foam has pretty much subsided and the mixture is beginning to thicken and look darker. If you use an instant-read thermometer, it should read between 155F – 160F.

5. Begin to slowly add the softened butter. Just add 2-3 pieces at a time, still whisking constantly. You want to incorporate the butter into the lemon mixture. If you simply add the butter and let it melt without whisking, the fat in the butter will separate and you won’t be able to incorporate it. You’ll simply end up with butterfat floating on top.

Adding the butter. Be sure to whisk constantly to make sure the butter is incorporated evenly into the lemon mixture. Do not let it simply melt on top.

6. After you have incorporated the butter, switch to either a wooden spoon or heat-proof spatula. Continue stirring constantly until the curd is thick enough to coat the back of the spoon or spatula.

Stirring the curd after the butter has been incorporated. Again, keep stirring constantly, making sure to keep, especially, the curd on the side and bottom of the bowl moving. That is the curd that will quickly over cook if it isn’t constantly stirred.

Coating the back of a wooden spoon. Running your finger through the curd on the spoon will test if it’s ready. If the curd doesn’t drip, it’s ready. This means that the eggs are cooked and your emulsion was successful.

7. When the curd is done, remove the bowl from the heat and pour into a clean bowl. Very carefully scrape or do not scrape the sides of the original bowl (it depends on how your final product looks). You can strain the mixture if you prefer. (Straining is recommended if you have larger pieces of zest or you want to smooth out a slightly lumpy curd.)

If, when you are done cooking, your eggs are curdled or scrambled, or your butter separates out, you can pour the mixture into a blender (not a food processor) and try to make a smooth curd. However, there’s no guarantee this will work; and if it does, you may still need to strain it to remove any remaining lumps of scrambled egg or the butter may separate out again.

8. To store, place a piece of plastic wrap directly on the surface of the curd and place in the refrigerator. Because of the high butter content, it will set up into a fairly firm spread. It will keep for 4 – 5 days.